Individuals with serious mental illness (SMI) die earlier than individuals in the general population, losing on average, 9-32 years of life. Much of the premature mortality among the SMI is due to medical comorbidities such as diabetes (DM) which has achieved epidemic proportions. While co-occurring SMI and DM (SMI-DM) are major public health problems, there are few effective treatment models for SMI patients with co-occurring illnesses that are widely utilizable in clinical settings. Practical treatment approaches are needed for patients with SMI-DM, because models of care that only focus on one condition without the other are likely to fail among individuals challenged with both SMI and DM. Effective models of care for mentally ill individuals with DM also should be generalizable and need to be readily adaptable to related medical conditions such as metabolic syndrome and obesity. The primary care setting offers a unique venue for teaching skills necessary for mental illness and medical self-management. Positive pilot research findings by these investigators have informed this project, which maps precisely onto NIMH Strategic Objective 3: Develop New and Better Interventions for Mental Disorders that Incorporate the Diverse Needs and Circumstances of People with Mental Illness. This project is a randomized, controlled trial (RCT) of a psychosocial intervention, Targeted Training in Illness Management (TTIM), intended to improve mental health symptoms, functioning, and quality of life as well as diabetes health outcomes in 100 individuals with SMI-DM vs. 100 individuals with SMI-DM receiving treatment as usual (TAU). TTIM is designed to overcome barriers to the complex problem of co- management of SMI and medical disorders and will focus on enhancing active participation of the SMI patients in the care of their illnesses. Nurse Educators will work together with Peer Educators to lead intervention sessions that facilitate communication, boost self-efficacy, and model behavioral changes. Secondary outcomes include adherence to medications for SMI and DM and engagement in healthy behaviors. Key factors previously identified as facilitators or barriers to optimal self-management of SMI and of DM will be targeted by the intervention and measured during the study. An important enhancement to the RCT is a qualitative assessment of facilitators and barriers for concurrent SMI-DM management from the perspective of individuals with SMI-DM. Interventions like TTIM that require relatively limited resources and that can be introduced into existing care systems with existing staff have the potential for wide-spread uptake in real-world settings and hold promise for improving care for high-risk, vulnerable individuals with SMI.